Different demands are made on the treads of a pneumatic vehicle tire. Since the tread is in direct contact with the roadway, it is important that the radially outer surface of the tread has advantageous properties in respect of adhesion, grip and braking properties for the entire duration of use. Moreover, good handling properties, a low rolling resistance and low noise emissions are advantageous. In the case of tires which are to be used in winter driving conditions, advantageous properties in respect of handling on snow, dry handling, wet braking properties, cornering stiffness and rolling resistance should be ensured.
In general, it is not possible to embody treads in such a way in respect of these properties that all the properties are improved to an equal extent. Tires, the tread surface of which has regions comprising different rubber compounds, are known.
Thus, U.S. Pat. No. 8,403,013 discloses a tire which has a tread region arranged radially on the outside which is formed from a material strip having two layers of different rubber compounds, wherein one compound is of electrically conductive configuration and the other compound is not of electrically conductive configuration. Here, the volume ratio of electrically conductive compound in the material strip is lower in the axial center of the tread than in the shoulder region. A tread of this kind is produced by winding an extruded multilayer material strip. A tire of this kind is said to have a low rolling resistance and a capacity for eliminating static charges while having a shorter production cycle time.
A tire of the type stated at the outset is known from EP 0 875 367 A2. Here, the tread segment extends over the entire axial width of the tread, and the rubber compounds of the two layers of the material strip differ in hardness. Through this combination of rubber compounds of different hardness, the tire is supposed to have advantageous adhesion while being simple to produce. However, treads with regions of different hardness have disadvantageous noise emission characteristics and disadvantageous nonuniform wear owing to the difference in the stiffness of these regions.